Need Opinions - Transmission Issue

[mattc95]

Hi All. Experiencing some trans issues. I drive a 97 Z71 with what I believe to be the original transmission. During my normal daily driving 10 minutes to work under 55mph I have no issues really. Say I have to run errands around town with a lot of stop and go, highway on and off ramps, stoplights, having to get on the gas to merge traffic etc. I begin to have issues. The trans will begin to shift hard through each early gear with a jolt I can feel in the cab as I accelerate. The truck seems to drive fine the next day until I have to push it hard again. I recently had to change multiple freeze plugs so I had to unbolt the trans and replace the fluid and coolant in that process. Trans still does the same jolt when changing gears after hard highway use. Any recommendations outside of the obvious of getting a new or refurbished trans? anyone experienced similar issue? Thanks

 

[stutaeng]

Do you have the P1870 code? How did the fluid look?

 

[JOHNGAAA1]

Did you check the throttle position sensor ? If it is bad it will give you a hard 1 - 2 shift.

 

[Schurkey]

Connect a scan tool, look for "codes", but also look at the transmission shift adaptations, trans temperature, verify torque converter clutch operation, etc.

As usual, "codes" can be helpful, but the real story is in the data stream.

 

[anthony112091]

I'm having the same issue but I have a 97 suburban k1500 but I do see a p1870 at times after hard highway use after I changed my fluid I don't get the code anymore but still get hard shifts on longer drives, my scan tool won't read Trans or see live data on it I can see all of that on motor though any recommendations on a budget friendly scanner that could read the transmission I been looking lately and too much false advertising to pull the trigger not knowing if it will work and allow me to see the data needed for this fix

 

[anthony112091]

Any luck?

 

[Kylebg94]

I'm having the same problem with my 95 5.7 Silverado. I've replaced the tps and that wasn't the culprit. Has anyone figured it out?

 

[NickTransmissions]

I'm having the same problem with my 95 5.7 Silverado. I've replaced the tps and that wasn't the culprit. Has anyone figured it out?

Yours may be a combination of things up to and including the PCM itself. Am curious to hear what the shop comes up with next week on your truck.

 

[Kylebg94]

Yeah me

Yours may be a combination of things up to and including the PCM itself. Am curious to hear what the shop comes up with next week on your truck.

Yeah, me too. The idle issue has been fixed. It appears the shifting issue may be a different problem. I've been doing some research, and on the 4160e transmissions. This symptom isn't exactly unheard of.

 

[Kylebg94]

So this is exactly what's happening with my truck. If I turn it off, and turn back on after a few minutes the harsh 1-2 shift goes away. It's a pressure issue. And it only occurs after driving on the highway for extended periods of time at speeds of 65 and 75 mph. And then slow down to a stop or low speed driving. Like inner city speeds.